Obama, South Korea's Lee aim to impede North Korea's nuclear program

President Barack Obama spoke to South Korean President Lee Myung-bak on Tuesday about North Korea's "highly provocative" nuclear test and agreed to work with the United Nations Security Council to address it, the White House said in a statement.

"President Obama unequivocally reaffirmed that the United States remains steadfast in its defense commitments to the Republic of Korea, including the extended deterrence offered by the US nuclear umbrella," the White House said of the two men's discussions. (Reuters)